Effects of combustion chamber geometry on combustion characteristics of a DI diesel engine fueled with calophyllum inophyllum methyl ester

This paper describes the results of an experimental investigation carried out in a single cylinder, variable compression ratio, CI engine fueled with Calophyllum Inophyllum Methyl Ester (CIME) blended with diesel. An earlier investigation made by the investigators using CIME blends in conventional Hemispherical Combustion Chamber (HCC), showed that the blend B20 provides the optimum results and hence B20 blend was used as a test fuel for further investigations. Further, the emissions like unburned hydrocarbon (UBHC), carbon monoxide (CO) and smoke have been noticed higher with diesel. In this investigation, attempts have been made to reduce the emissions and improve the combustion characteristics by enhancing the fuel-air mixture preparation and its turbulence by changing the design of piston bowl geometry. For this, a Modified Hemispherical Combustion Chamber (MHCC) has employed and the results were compared with conventional Hemispherical Combustion Chamber (HCC). The fuel-air mixture formation in the cylinder was simulated at different positions of the piston (at TDC, mid of stroke and at BDC) using Ansys Fluent software. Conclusively, from the investigations, MHCC was recognized as an ideal choice of combustion chamber design for the entire range of operations of the engine using the blend (B20) than that of HCC.